1. Field of the Invention
The present invention relates to a liquid discharge head for discharging desired liquid by generation of a bubble induced by action of thermal energy on the liquid, and more particularly to the configuration of a liquid discharge head having a movable member which is displaced by the generation of the bubble, a producing method therefor and a liquid discharge apparatus utilizing the liquid discharge head.
The present invention is applicable to an apparatus such as a printer for recording on various recording media such as paper, yarn, fiber, cloth, metal, plastics, glass, timber or ceramics, a copying apparatus, a facsimile apparatus provided with a communication system, or a word processor equipped with a printer unit, or to industrial recording apparatus combined with various processing apparatus.
In the present invention, the xe2x80x9crecordingxe2x80x9d means not only providing the recording medium with a meaningful image such as a character or a graphics but also with a meaningless image such as a pattern.
2. Related Background Art
There is already known so-called bubble jet recording method, namely an ink jet recording method of providing ink with an energy such as heat to cause a state change (bubble generation) involving an abrupt volumic change in the ink, discharging ink from the discharge opening by an action force based on such state change and depositing the ink onto a recording medium to form an image. The recording apparatus employing such bubble jet recording method is generally provided, as disclosed in the U.S. Pat. No. 4,723,129, with a discharge opening for discharging ink, an ink path communicating with the discharge opening and an electrothermal converting member provided in the ink path and serving as energy generating means for generating energy for discharging the ink.
Such recording method has various advantages for example of recording an image of high quality at a high speed with a low noise level, and recording an image of a high resolution or even a color image with a compact apparatus since, in the head executing such recording method, the ink discharge openings can be arranged with a high density. For this reason, the bubble jet recording method is recently employed in various office equipment such as printers, copying machines, facsimile apparatus etc., and even in industrial systems such as fabric dyeing apparatus.
With the spreading of the bubble jet technology into various fields, there are appearing various demands explained in the following.
For example, in order to satisfy a demand for improving the energy efficiency, there is conceived optimization of the heat generating member, such as adjustment of the thickness of the protective film for the heat generating member. This method is effective in improving the efficiency of propagation of the generated heat to the liquid.
Also for obtaining the image of high quality, there is proposed a driving method for liquid discharge capable of realizing a faster ink discharging speed and satisfactory ink discharge based on stable bubble generation, and, for achieving high-speed recording, there is proposed an improved shape of the liquid path for realizing the liquid discharge head with a faster refilling speed of the liquid into the liquid path.
For example the Japanese Patent Application Laid-Open No. 9-201966 discloses a configuration of providing a movable member in the liquid path, thereby stabilizing the discharge. Also the Japanese Patent Application Laid-Open No. 9-48127 discloses a configuration of controlling the moving range of the movable member. However these references do not teach the specific method of forming these configurations.
The object of the present invention is to provide a liquid discharge head capable of attaining both the improvement in the discharge characteristics and the improvement in the frequency of liquid discharge with a simple configuration, a producing method therefor and a liquid discharge apparatus.
The foregoing object can be attained, according to the present invention, by a liquid discharge head provided with an element substrate and a ceiling plate fixed in a mutually opposed state, plural liquid path lateral walls provided between the ceiling plate and the element substrate and defining plural liquid flow paths, plural discharge energy generating elements arranged in parallel on the surface of the element substrate so as to be respectively positioned in the plural liquid paths, plural movable members in the form of a cantilever supported at an end, provided on the element substrate so as to be respectively opposed to the plural discharge energy generating elements and provided with fixed ends at the upstream side in the liquid flowing direction in the liquid paths and free ends at the downstream ends, and plural projections provided on the ceiling plate for respectively limiting the amount of displacement of the plural movable members, the element substrate and the ceiling plate having similar materials, wherein the liquid path lateral walls are formed on the element substrate, and, on the ceiling plate, there is provided an engaging layer having recesses for fitting with the upper end faces of the liquid path lateral walls.
Further, in order to attain the above object, the invention provides a liquid discharge head provided with an element substrate and a ceiling plate fixed in a mutually opposed state, plural liquid path lateral walls provided between said ceiling plate and said element substrate and defining plural liquid flow paths, plural discharge energy generating elements arranged in parallel on the surface of said element substrate so as to be respectively positioned in said plural liquid paths, plural movable members in the form of a cantilever supported at an end, provided on said element substrate so as to be respectively opposed to said plural discharge energy generating elements and provided with fixed ends at the upstream side in the liquid flowing direction in said liquid paths and free ends at the downstream ends, and plural projections provided on said ceiling plate for respectively limiting the amount of displacement of said plural movable members, said element substrate and said ceiling plate having similar materials, wherein said liquid path lateral walls are formed on said element substrate, and, on said ceiling plate, there is provided an engaging layer having said projections.
In such configurations, because the element substrate and the ceiling plate contain similar materials, these components have little difference in the linear expansion coefficient, whereby there can be suppressed the deformation resulting from the rise in temperature after assembling. Also by forming a projection with a thick film process employing silicon nitride on a silicon substrate, there can be obtained a chemically stable configuration which is not affected by the ink components. Also as the liquid path lateral walls are formed on the element substrate and the ceiling plate is provided with recesses for engaging with the upper end faces of the liquid path lateral walls, there can be improved the adhesion property of the element substrate, liquid path lateral walls and ceiling plate, and there can also be improved the hermetic property of the liquid path.
It is also preferred to include a step of depositing an inorganic material layer on the ceiling plate consisting of an inorganic material and partially removing such inorganic material layer to form the projection and the recess.
According to the present invention, the liquid path lateral wall of the substrate and the recess of the ceiling plate are mutually fitted to improve the hermetic property of the liquid path. Also the substrate and the ceiling plate can be adhered easily and precisely by closing the recess of the ceiling plate and abutting the ceiling plate and the substrate at the adhering operation.
Furthermore, by forming all the ceiling plate, projection and element substrate with inorganic materials, there can be suppressed the deformation resulting from the temperature change after the manufacture because of the limited difference in the linear expansion coefficients.